The Surgery Branch is vigorously involved in the assessment of the efficacy of total parenteral nutrition as a means of nutritional support of the cancer-bearing host. These studies are directed at conventional nitrogen balance, weight change, and with specific attention to muscle protein breakdown as assessed by 3-methyl histidine excretion in the urine. Studies are currently being initiated to examine specific substrate metabolism in these patients, particularly alanine and glucose. In addition, the first prospective randomized protocol of the use of total parenteral nutrition as an adjunct to aggressive chemo- and radiotherapy has been initiated. Determination of specific DNA activity and conventional parameters of tumor and host growth in animals bearing a rat sarcoma reveal that the tumor is relatively resistant to substrate manipulation, e.g., total starvation, protein depletion, or cortisone administration while the host bears a marked nutritional insult even in the early stages of the cancer-bearing state. An effort has been made to nutritionally deprive human melanoma and osteosarcoma tissue cell lines of essential nutrients along with appropriate fibroblastic controls. BIBLIOGRAPHIC REFERENCES: Reilly, J.T., Goodgame, J.T., Jones, D.C., and Brennan, M.F.: DNA synthesis in rat sarcoma and liver: The effect of starvation. J. Surg. Res. 22:281-286, 1977. Brennan, M.F., and Goodgame, J.T.: Nutrition in cancer. Host-tumor interaction during varying conditions of substrate availability. In Richards, J.R., and Kinney, J.M. (Eds.): Nutritional Care of the Critically Ill. London, Churchill, Livingston, 1977.